1. Field of the Invention
The present invention relates to a reflex, magnifying optical system.
2. Description of the Related Art
Recently, accompanying demand for smaller sized imaging devices, there is demand for smaller sized lenses mounted on the imaging devices as well. In response, reflex optical systems employing a prism in an optical path to refract the optical path have been proposed, such as those disclosed in Japanese Patent Application Laid-Open Publication Nos. 2005-128065, 2004-334070, 2004-333721, 2007-232974, and 2004-163477.
Reflex optical systems disclosed in the publications achieve a reduced depth (thickness) by refracting the light path. Consequently, mounting of these reflex optical systems has enabled imaging devices to have shortened depths as well.
The lens arranged on the incident side or on the emission side of the prism that refracts the optical path tends to have high error sensitivity (e.g., tilt error). High error sensitivity is undesirable and leads to significant deterioration of optical performance. Each of the reflex optical systems disclosed in the publications place great emphasis on achieving reductions in the size of the optical system and in doing so, a problem arises in that the means for reducing the error sensitivity is insufficient.